Re: stable backport request for stmmac DSA tag fixes

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On Wed, Feb 27, 2019 at 05:38:27PM +0100, Greg KH wrote:
> On Wed, Feb 27, 2019 at 05:19:11PM +0100, Niklas Cassel wrote:
> > Hello,
> > 
> > I would like to request:
> > 
> > 8cad443eacf6 ("net: stmmac: Fix reception of Broadcom switches tags")
> > (was first included in v4.16)
> > 
> > and
> > 
> > 565020aaeebf ("net: stmmac: Disable ACS Feature for GMAC >= 4")
> > (was first included in v4.17)
> 
> This patch looks like it needs to be applied to 4.9.y as well, can you
> provide a backported version?

Actually, the second patch depends on the first patch, since it changes
code added by the first patch, so these should be backported together.

However, there was a trivial one liner conflict in v4.9 when
cherry-picking the first patch, so I attached a backport.
After this, the second patch applies on v4.9 without conflicts.


Kind regards,
Niklas

> 
> > to be backported to linux-stable/linux-4.14.y
> > 
> > Without these, packets will get stripped twice (corrupted)
> > when using stmmac with switches that uses DSA tags.
> 
> Both now queued up, thanks.
> 
> greg k-h
>From 7228f30ed3900af939fd69e807b7a35ce545efe9 Mon Sep 17 00:00:00 2001
From: Florian Fainelli <f.fainelli@xxxxxxxxx>
Date: Thu, 18 Jan 2018 15:12:21 -0800
Subject: [PATCH] net: stmmac: Fix reception of Broadcom switches tags

Broadcom tags inserted by Broadcom switches put a 4 byte header after
the MAC SA and before the EtherType, which may look like some sort of 0
length LLC/SNAP packet (tcpdump and wireshark do think that way). With
ACS enabled in stmmac the packets were truncated to 8 bytes on
reception, whereas clearing this bit allowed normal reception to occur.

In order to make that possible, we need to pass a net_device argument to
the different core_init() functions and we are dependent on the Broadcom
tagger padding packets correctly (which it now does). To be as little
invasive as possible, this is only done for gmac1000 when the network
device is DSA-enabled (netdev_uses_dsa() returns true).

Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Acked-by: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/common.h      |  2 +-
 .../net/ethernet/stmicro/stmmac/dwmac1000_core.c  | 12 +++++++++++-
 .../net/ethernet/stmicro/stmmac/dwmac100_core.c   | 15 +++++++++++++--
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 12 +++++++++++-
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |  2 +-
 5 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index 6d2de4e01f6d..b35299620052 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -450,7 +450,7 @@ struct mac_device_info;
 /* Helpers to program the MAC core */
 struct stmmac_ops {
 	/* MAC core initialization */
-	void (*core_init)(struct mac_device_info *hw, int mtu);
+	void (*core_init)(struct mac_device_info *hw, struct net_device *dev);
 	/* Enable and verify that the IPC module is supported */
 	int (*rx_ipc)(struct mac_device_info *hw);
 	/* Dump MAC registers */
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
index 7d19029e2564..b953ea2f808f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
@@ -29,18 +29,28 @@
 #include <linux/crc32.h>
 #include <linux/slab.h>
 #include <linux/ethtool.h>
+#include <net/dsa.h>
 #include <asm/io.h>
 #include "stmmac_pcs.h"
 #include "dwmac1000.h"
 
-static void dwmac1000_core_init(struct mac_device_info *hw, int mtu)
+static void dwmac1000_core_init(struct mac_device_info *hw,
+				struct net_device *dev)
 {
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value = readl(ioaddr + GMAC_CONTROL);
+	int mtu = dev->mtu;
 
 	/* Configure GMAC core */
 	value |= GMAC_CORE_INIT;
 
+	/* Clear ACS bit because Ethernet switch tagging formats such as
+	 * Broadcom tags can look like invalid LLC/SNAP packets and cause the
+	 * hardware to truncate packets on reception.
+	 */
+	if (netdev_uses_dsa(dev))
+		value &= ~GMAC_CONTROL_ACS;
+
 	if (mtu > 1500)
 		value |= GMAC_CONTROL_2K;
 	if (mtu > 2000)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac100_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac100_core.c
index 6418b2e07619..3e2331d01cd2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac100_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac100_core.c
@@ -29,15 +29,26 @@
 *******************************************************************************/
 
 #include <linux/crc32.h>
+#include <net/dsa.h>
 #include <asm/io.h>
 #include "dwmac100.h"
 
-static void dwmac100_core_init(struct mac_device_info *hw, int mtu)
+static void dwmac100_core_init(struct mac_device_info *hw,
+			       struct net_device *dev)
 {
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value = readl(ioaddr + MAC_CONTROL);
 
-	writel((value | MAC_CORE_INIT), ioaddr + MAC_CONTROL);
+	value |= MAC_CORE_INIT;
+
+	/* Clear ASTP bit because Ethernet switch tagging formats such as
+	 * Broadcom tags can look like invalid LLC/SNAP packets and cause the
+	 * hardware to truncate packets on reception.
+	 */
+	if (netdev_uses_dsa(dev))
+		value &= ~MAC_CONTROL_ASTP;
+
+	writel(value, ioaddr + MAC_CONTROL);
 
 #ifdef STMMAC_VLAN_TAG_USED
 	writel(ETH_P_8021Q, ioaddr + MAC_VLAN1);
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index 51019b794be5..16b7f9ed3785 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -17,16 +17,26 @@
 #include <linux/slab.h>
 #include <linux/ethtool.h>
 #include <linux/io.h>
+#include <net/dsa.h>
 #include "stmmac_pcs.h"
 #include "dwmac4.h"
 
-static void dwmac4_core_init(struct mac_device_info *hw, int mtu)
+static void dwmac4_core_init(struct mac_device_info *hw,
+			     struct net_device *dev)
 {
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value = readl(ioaddr + GMAC_CONFIG);
+	int mtu = dev->mtu;
 
 	value |= GMAC_CORE_INIT;
 
+	/* Clear ACS bit because Ethernet switch tagging formats such as
+	 * Broadcom tags can look like invalid LLC/SNAP packets and cause the
+	 * hardware to truncate packets on reception.
+	 */
+	if (netdev_uses_dsa(dev))
+		value &= ~GMAC_CONFIG_ACS;
+
 	if (mtu > 1500)
 		value |= GMAC_CONFIG_2K;
 	if (mtu > 2000)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 65ed02bc3ea3..602bf3f9eebf 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1716,7 +1716,7 @@ static int stmmac_hw_setup(struct net_device *dev, bool init_ptp)
 	}
 
 	/* Initialize the MAC Core */
-	priv->hw->mac->core_init(priv->hw, dev->mtu);
+	priv->hw->mac->core_init(priv->hw, dev);
 
 	ret = priv->hw->mac->rx_ipc(priv->hw);
 	if (!ret) {
-- 
2.20.1


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